Tonami Ken-ichi, Ericson Dan
Oral Diagnosis and General Dentistry, Dental Hospital, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, 113-8549, Tokyo, Japan.
Acta Odontol Scand. 2005 Feb;63(1):17-20. doi: 10.1080/00016350410010090.
The purpose of this study was to describe the protein profile of pepsin-digested carious and sound dentine using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Carious and sound dentine powder was decalcified using 10% EDTA at pH 7.4 for 48 h. The decalcified pellet was digested using pepsin at pH 2 under sequenced conditions: at 4 degrees C for 24 h, a further 24 h at 23 degrees C, and finally for 24 h at 37 degrees C. After every step, the soluble fraction was separated by centrifugation and analyzed in 15% SDS-PAGE. Two bands at 56 and 62 kDa could be observed in carious dentine digests and were considered specific carious bands. Similar bands could be observed in sound dentine samples, but only after pepsin digestion at higher temperatures (23 degrees C and 37 degrees C). Pepsin digests non-helical collagen and the triple helix structure of collagen is lost when the temperature rises. The bands at 56 and 62 kDa in sound dentine specimens thus represent pepsin-cleaved collagen. There is a possibility that the specific carious bands in carious dentine represent collagen decomposed in a manner similar to the way pepsin digests native dentine collagen at 23 degrees C and 37 degrees C.
本研究的目的是利用十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）描述经胃蛋白酶消化的龋损牙本质和健康牙本质的蛋白质谱。龋损牙本质粉和健康牙本质粉在pH 7.4的10%乙二胺四乙酸（EDTA）中脱钙48小时。脱钙后的沉淀在pH 2的条件下用胃蛋白酶按以下顺序消化：4℃下24小时，23℃下再24小时，最后37℃下24小时。每一步之后，通过离心分离可溶性部分，并在15%的SDS-PAGE中进行分析。在龋损牙本质消化物中可观察到两条分别位于56 kDa和62 kDa的条带，被认为是龋损特异性条带。在健康牙本质样本中也可观察到类似条带，但仅在较高温度（23℃和37℃）下经胃蛋白酶消化后才出现。胃蛋白酶可消化非螺旋状胶原蛋白，温度升高时胶原蛋白的三螺旋结构会丢失。因此，健康牙本质标本中56 kDa和62 kDa的条带代表胃蛋白酶切割的胶原蛋白。龋损牙本质中的特异性龋损条带有可能是以类似于胃蛋白酶在23℃和37℃下消化天然牙本质胶原蛋白的方式分解的胶原蛋白。
